Paul Rudd Details His 'Very Restrictive' “Ant-Man” Diet: 'My Reward Was Sparkling Water'

"That's how horrible the diet was," the actor joked during a recent appearance on the 'Off Menu' podcast

Paul Rudd is reflecting on the extreme diet and exercise regime he had to undertake to get into fighting form for the Ant-Man movies.

During an appearance on Tuesday's episode of the Off Menu podcast, the actor, 54, admitted that his eating plan was so "restrictive" that "my reward was sparkling water."

"That's how horrible that diet was," he recalled. "It was like, 'Oh, alright, I'm going to have some sparkling water now. I've earned it. Train, work out … so I was having a lot of sparkling water."

Rudd went on to joke that he even gravitated toward Pellegrino because the Italian mineral water has a "softer carbonation" than other bubbly water brands.

"Too much carbonation, I would have exploded at that size. One bubble would take me out," he said with a laugh.

When hosts Ed Gamble and James Acaster asked if the water truly felt like a treat, Rudd insisted it did. "Yeah, it was great," he said, before quickly noting, "It wasn't flavored — I wasn't going to go crazy. But it was a treat."

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Rudd then went on to explain that he adjusted surprisingly well to his low-calorie diet. "Once you're in it, it's actually not too hard. And I think you guys can guess that I'm okay with having really boring food over and over again. You get into the groove of it," he explained.

The actor also said that he was surprised to find that eating lighter meals energized him. "You feel good — waking up with tons of energy is the strangest sensation. That was new for me," he recalled.

When the hosts inquired if he "compared notes" with his costars, who were also following special diets to get in shape for the films, Rudd poked fun at himself with his trademark self-deprecating humor.

"I think I worked out harder than everyone, I would eat better than everyone and I'd look worse than all of them," he lamented. "I had to work out all the time, eat perfectly, just to kind of look bad."

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Rudd followed a similarly rigorous training program for his 2019 Marvel movie Avengers: Endgame, and he jokingly recalled how costar Chris Hemsworth showed him up on set.

"I remember on Endgame, Chris Hemsworth would have these Tupperware containers and he's eating this gruel of just a mash of stuff. And he's working out. You stand next to a guy like that, I was like, 'What's the point of any of this? Why am I killing myself when that can exist? I can never achieve that,' " he said.

"Ant-Man isn't Thor. But I tried to work out like Thor, and it didn't work," Rudd added.

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While Rudd may feel like he doesn't quite measure up to the Australian action star, he did claim the title of PEOPLE's Sexiest Man Alive in 2021. After Chris Evans succeeded him in 2022, the Only Murders in the Building star even offered to help prepare him to wear the crown.

"I said, 'Look, here's the deal, Chris. This comes with a lot of responsibility,'" he recounted to PEOPLE. "'If you want to sit down and maybe have like, we'll probably need to spend the day, it's going to take hours, because there's a lot you have to live up to and there's a lot expected of you. And if you want to have like a real strategy session or what it's been like and what's required, I'm available.' And I gave him a series of days."

However, it seemed Evans wasn't interested in Rudd's little "strategy session."

"Yeah, he's never returned one text," Rudd said. "[But he's] absolutely busy. He's the Sexiest Man Alive. There are no days off for that."

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